400621878721 has 2 divisors, whose sum is σ = 400621878722. Its totient is φ = 400621878720.

The previous prime is 400621878707. The next prime is 400621878737. The reversal of 400621878721 is 127878126004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 363078553600 + 37543325121 = 602560^2 + 193761^2 .

It is a cyclic number.

It is not a de Polignac number, because 400621878721 - 2¹⁷ = 400621747649 is a prime.

It is not a weakly prime, because it can be changed into another prime (400621878751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200310939360 + 200310939361.

It is an arithmetic number, because the mean of its divisors is an integer number (200310939361).

Almost surely, 2^400621878721 is an apocalyptic number.

It is an amenable number.

400621878721 is a deficient number, since it is larger than the sum of its proper divisors (1).

400621878721 is an equidigital number, since it uses as much as digits as its factorization.

400621878721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 301056, while the sum is 46.

The spelling of 400621878721 in words is "four hundred billion, six hundred twenty-one million, eight hundred seventy-eight thousand, seven hundred twenty-one".